Some of the 10 suspected mail bombs addressed to high-profile Democrats and others over the last few days were flawed and not capable of exploding, while others have yet to be fully analyzed, several investigators said Thursday.

In some cases, the flaws were substantial. In others, more subtle, they said.

NBC News: Law enforcement sources say that at this point in the review of the bombs it is clear that some were incapable of exploding. Whether that was a design flaw or intentional is not yet known. Analysis is ongoing

The news, expected to be detailed at a joint NYPD/FBI briefing in New York shortly, comes after investigators said the devices appeared poorly made and that it was unclear if they were hoaxes or simply cases of bad construction. Earlier in the investigation, officials in multiple states had described the items as live explosives and a number of senior bomb techs briefed on the probe said they had all the components necessary for successful explosions.

Investigators cautioned that the analysis is far from complete, and they say anyone who encounters one of the parcels should treat it as dangerous.

None of the 10 seized devices detonated, and no one has been hurt.

Breitbart reported later on Thursday: "During a press briefing Thursday, New York officials were tight-lipped about whether the devices were functional but did confirm reports that the powder substance accompanying some of the devices did not pose a biological threat. Asked if the bombs posed any threat, NYPD Commissioner James O’Neill said, 'We're taking this seriously. We are treating them as live devices… as far as hoax devices, we’re not treating it that way.'"

Despite conservatively tens of thousands of reports from the media that these were "pipe bombs" and "explosives," there's still zero evidence they were actually "functional" as CNN's Jake Tapper and many others claimed.

Packages to Soros, Obamas, Clintons, Brennan c/o CNN, Holder -- these devices, per law enforcement sources, were rudimentary but functional.